The present invention relates to a heater assembly adapted to be secured to a glass surface, and particularly a glass surface defined by a rear window of an automobile so that the heater assembly functions as a defroster and/or defogger to permit unmarred vision therethrough.
Rear window defrosters can be supplied as original equipment in an automobile in which case the heating elements are usually embedded directly within the window glass. The heater assembly involved herein, however, is of the type which is not provided as original equipment with the automobile but which is applied to the rear window of an automobile not equipped with an embedded heater assembly.
U.S. Pat. No. 3,757,087 illustrates a heater assembly consisting of a heating array supported by a backing sheet which enables the array to be secured onto the window, after which the backing sheet is peeled off, leaving only heater elements on the rear window of the automobile. By passing electrical current through the array, there is generated heat which, in turn, causes the defrosting and defogging of the rear window to which the array is secured.
In order to more closely simulate a rear window defroster of the type which is embedded within the glass window as part of the original equipment, it has become desirable to define the heating array by a plurality of parallel spaced horizontally extending narrow heater elements whose opposite ends are electrically connected to a pair of electrical conductive busbars to define a complete electrical circuit for the heater elements. Placing a suitable voltage across the opposite busbars will cause electrical current to flow through the heater elements to provide the necessary heat so that the defroster and defogging function can be performed. An example of such arrangement is shown in U.S. Pat. No. 4,213,028.
In the type of construction described in U.S. Pat. No. 4,213,028, it is of great importance to secure the opposite ends of the heater elements so the busbars in a way which will be simple, which will insure good electrical contact between the heater elements and the busbars, which will maintain good physical securement of the heater elements to the busbars and good securement of the busbars to the rear window. This is attempted in U.S. Pat. No. 4,213,028 by first placing the two busbars in position on the window and thereafter laying the several electrical heating elements across the window with the ends thereof overlapping the busbars. While such arrangement has been satisfactory to some degree, it does require that the installer commit himself to the overall width of the heating array when first placing the busbars in position, before the heater elements are themselves placed on the window. Further, in such arrangement, there is a relatively small portion of the heater element in engagement with the busbar, such portion necessarily being limited to the width of the busbar. Accordingly, both the physical and electrical connections between the heater elements and the busbar are limited in degree.
It is therefore an object of the present invention to provide an improved heater assembly which will enable more secure electrical and physical connections between the ends of the heater elements and the associated busbars.